JPH081280Y2 - Balancer for cargo handling - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is of a type in which a load is manually moved in the XY directions (horizontal direction) and the vertical movement (Z direction) is controlled by a torque motor. Regarding improvement of the balancer for cargo handling.

[Conventional technology]

A conventional cargo handling balancer that uses a torque motor controls the rotation speed of the torque motor that raises and lowers the arm and keeps the arm in equilibrium with a torque commensurate with the weight of the load. The structure allows the arm to be horizontally moved within the working range of the machine simply by hanging the baggage. Thus, such a cargo handling balancer is used for carrying work such as palletizing and depalletizing luggage, and carrying jigs and instruments that are attached to and detached from the processing machine.The maximum carrying work range is the length of the arm. And the arm drive is then designed to transfer from the motor to the arm sufficient torque to balance and displace the arm according to its length.

[Problems to be solved by the invention] However, if the arm length of the cargo handling balancer designed as described above is simply changed in accordance with the required specifications of the maximum working range, the arm is long unless the arm drive section is changed. Since the maximum suspension load is reduced and the lifting speed also changes with the arm ratio, the length of the arm can be reduced without lowering the maximum lifting capacity of the load or making the arm lifting speed unstable. In order to change it according to the required specifications of the maximum working range, the structure of the arm drive unit had to be changed or redesigned.

The object of the present invention is to easily and easily change the length of an arm for various required specifications of the maximum work range without causing a decrease in the maximum hanging capacity of the load and an instability of the arm lifting speed. It is to provide a cargo handling balancer that can respond immediately.

[Means for solving the problem]

As a means for solving the above problems, a cargo handling balancer of the present invention is provided with a joint portion whose lateral length is variably set in an intermediate portion of an arm for supporting a load, and an arm driving portion. , Adopts a structure in which the transmission torque from the torque motor to the screw nut can be switched according to the set length of the arm.

[Action]

The torque motor is driven to transmit the rotation torque to the screw nut, and the screw shaft fitted to the nut is moved up and down to drive the arm up and down. At this time, the maximum load work range is determined by the length of the arm, but if the arm is relatively long, the distance from the center of gravity of the load to the support point of the arm by the screw shaft becomes long, and the load of the same load is increased. If you want to suspend the, you need a larger torque. For various required specifications of the maximum work range of luggage,
In order to widen the working range, the longer the arm is set, the larger the torque transmitted from the torque motor to the screw nut, so that the torque switching mechanism of the arm drive changes the gear ratio of the torque transmission path. To do.

〔Example〕

FIG. 1 shows an overall view of an embodiment of the present invention.
The cargo handling balancer shown in the same figure is rotatably provided on a column 3 standing on a base 1 through bearings 5 and 5, and a side frame 7 is provided opposite to the front and back sides of FIG. Reference numerals 7 and 7 denote an arm 9 configured by a later-described first parallel link mechanism, a drive unit 11 that drives the arm 9 up and down,
Control unit of the drive unit 11 incorporating a microcomputer
13 and an operation unit 15 are provided. The cargo handling balancer may be provided with a track laid on the ceiling rotatably on a movable table running in the X and Y axis directions.

This cargo handling balancer includes an attachment mounting portion 17 pivotally supported by a second parallel link mechanism 22 described later, and an attachment (not shown) for supporting luggage such as a holding hand or a vacuum suction hand equipped with fingers.
Is attached, the operator grips the vicinity of the luggage support attachment, the turning operation and the forward / backward movement operation of the arm 9 are manually performed, and the vertical movement of the arm is controlled by a microcomputer according to the operation program of the operation unit 15. It is designed to be powered by.

The arm 9 includes a parallelogram-shaped first parallel link mechanism 21 and a second parallel link mechanism 22 that share a vertical link 20, and is pivotally supported by the side frames 7, 7. That is, the first
The parallel link mechanism 21 includes a pair of horizontal links 23, 24 and a pair of vertical links 20, 26, and the support shafts 27 to 30 constitute a joint portion. Further, the second parallel link mechanism 22 includes a pair of horizontal link plates 33, 34 and a pair of vertical links 20, 36, and the support shafts 28, 37-3.
The joint is composed of 9. Further, in addition to the horizontal link 40 and the vertical link 41, a third parallel link mechanism 43 utilizing a part of the horizontal link 24 and the link plate 33 is provided.
The rotation of the joint part 28 as a fulcrum is suppressed, the attachment mounting part 17 and the link plate 34 are assisted in parallel movement, and the link plate 34 is always kept horizontal. The support shafts 28, 44 to 46 of the third parallel link mechanism 43 form a joint portion. The lateral link 24 has side frames 7, 7 punched out, and a balance weight 47 is fixed to the base of the lateral link 24 so as to be positionally adjustable.

The horizontal link 23 has a slide structure for adjusting the length thereof. For example, as shown in FIG. 7, this slide structure has a distal end link 23A slidably fitted in a hollow proximal end link 23B, By adjusting the output of the link 23A by fixing the tip link 23A with a screw at an appropriate position, the horizontal link 2
It is designed to determine the length of 3. Similarly link 24
Is two links 24A, 24B, and link 40 is two
The links 40A and 40B of the book are so constructed that their lengths can be adjusted respectively. Thereby, the length of the arm 9 can be set arbitrarily. In addition, in FIG. 1, 23C, 24C, and 40C are joint portions of the horizontal links 23, 24, and 40 when set to a desired length.

Further, the vertical link 20 also has a slide structure for adjusting the length thereof, the distal end link 20A is slidably fitted into the hollow base end link 20B, and the distal end link 20A is screwed at an appropriate position. By doing so, the length of the vertical link 20 is determined by adjusting the condition of the link 20A. The vertical link 36 is divided into three members 36A to 36C, opposite screws of the opposite ends of the members 36A and 36C are provided with opposite screws, and both ends of the intermediate member 36B are screw-fitted thereto.
The length of the vertical link 36 can be adjusted by turning the intermediate member 36B. Thus, the length of the arm 9 in the vertical direction can be set arbitrarily. In addition, in FIG. 1, 20C, 36D, and 36E are joint portions of the vertical links 20 and 36 when set to a desired length.

The support structure of the arm 9 for the side frames 7 and 7 is
The guide roller 50 axially supported by the support shaft 30 is supported by the lateral groove guide 51 and the upper guide 52 of the side frame 7 so as to be horizontally movable, and the guide rollers 53, 54 pivotally supported by the support shafts 45, 46, respectively. It is configured to be fitted into the vertical groove guide 55 of the side frame 7 so as to be supported so as to be vertically movable.

Therefore, when the link mechanism moves the guide rollers 53 and 54 together with the vertical link 41 up and down along the vertical groove guide 55, the vertical position of the arm 9 is determined. Especially the third parallel link mechanism
Due to the action of 43, the direction of the vertical link 41 is changed to the vertical groove guide 55.
As a result of being constrained to the vertical direction and being restricted in the vertical direction, the directions of the first parallel link mechanism 21 and the second parallel link mechanism 22 change, and the inclinations of the link plates 33 and 34 do not change at all. The inclination of the load gripped by the attachment does not change regardless of the vertical movement of the arm 9, and is always kept horizontal or vertical. Incidentally, FIG. 2 shows the movable range of the vertical movement of the arm.

In the parallel link structure arm 9, the vertical link 2
The lengths of 0, 36 and the horizontal links 23, 24, 40 are set to desired lengths under the condition that the centers of the support shafts 30, 46, 39 are arranged on a straight line. Due to this condition, the center of the support shafts 29, 30, 46 (points A, B,
C) with 3 vertices and the center of spindle 28,39,46 (point C,
It is similar to a triangle having D, E) as three vertices, and a triangle CFG (point F passes through the center of gravity of the balance weight 47 and is parallel to the link 26 and a straight line including points C and B). Intersection)
Is also similar to the triangle. Therefore, the ratio of the length DC, the length CB, and the length BF is constant regardless of the position of the point C in the vertical groove guide 55 and the point B in the horizontal groove guide 51 within the movable range.
The weight of the load acting on the point is Fd, the force acting on the point C is Fc,
Assuming that the reaction force acting on the B point is Fb and the weight of the balance weight 47 is Ff, from the balance of the moment around the C point and the moment around the B point, Fd ・ BD-Fc ・ CB-Ff ・ BF = 0 The relationship can be obtained, and if this is rearranged, it is expressed as Fc = Fd.BD / CB-Ff.BF / CB. As a result, if the weight Fd of the load is determined, the forces Fb and Fc are constant regardless of the vertical position of the arm 9.
Therefore, if the point C is supported by a force that balances the weight Fd of the load, the balance is maintained no matter how the point D, that is, the height of the load changes. In the above description, the weight of the arm is ignored and it is assumed that the center of gravity of the luggage passes through the point D for easy understanding. Actually, it is located near the center of the attachment mounting portion 17, depending on the shape of the luggage.

Next, the drive unit 11 that moves the link 41 up and down will be described.

The drive unit 11 includes a torque motor 60 as its drive source. The torque motor 60 is often used in a servo mechanism and is a reversible rotatable motor capable of varying torque and speed in accordance with changes in drive voltage due to phase control and the like, and produces the largest torque even when stationary or close to it. have. The reversible rotation of the tokule motor 60 is converted into vertical movement of the ball screw shaft 61, and the ball screw shaft 61 is connected to the link 41. The ball screw shaft 61 and the link 41 are connected to each other by, for example, fitting and fixing the upper end portion of the ball screw shaft 61 to the connecting pin 62 inserted into the support shaft 45 as shown in FIG.

The torque motor 60 is mounted on the bottom surface side of a base housing 65 fixed to the side frame 7 as shown in FIG.
Project inside the cover housing 67 fixed on the base housing 65. Large diameter teeth 68A on the motor shaft 66
A driving gear 68 having a small diameter tooth 68B and a small diameter tooth 68B integrally concentrically is fixed by a key 69, and a gear 70 that meshes with the small diameter tooth 68B is arranged, and a small diameter tooth 71B and the small diameter tooth 68 that mesh with the large diameter tooth 68A.
Large-diameter teeth 71A meshing with B are spaced apart from each other, and concentric and integrally formed switching gears 71 are arranged and axially supported by upper and lower housings 65 and 67, respectively.

The gear 70 and its supporting shaft 73 rotate integrally, and the disc 74 is fixed to the upper end portion of the supporting shaft 73, and below the disc 74 is attracted by the electromagnetic action of the solenoid 76 against the elastic force of the compression coil spring 75. A movable disc 77 is placed, and both discs 74,7
An electromagnetic brake that interposes a brake pad 79 between 7 and presses the brake pad 79 against the fixed disc 74 by the elastic force of the compression coil spring 75 when the solenoid 76 is demagnetized, thereby suppressing the rotation of the motor shaft 66 due to the load torque. Are configured.

The switching gear 71 loosely fitted on the support shaft 80.
As shown in FIGS. 5 and 6, is fitted so as to be slidable in the axial direction in association with the movement of the support arm 78 that holds the small-diameter tooth 71B from the vertical direction, and corresponds to the axial position. do it,
The meshing state between the large diameter teeth 71A and the small diameter teeth 68B or the meshing state between the small diameter teeth 71B and the large diameter teeth 68A is selectively switched. In addition, this meshing state switching setting is performed by shifting the knob 89 fitted to the support arm 78 from the outside through the elongated hole 83 formed in the back surface of the cover housing 67 through the disc spring 86 in the vertical direction to set the disc at the desired position. This is done by tightening and fixing the knob 89 against the elastic force of the spring 86.

A hollow holder shaft 82 having a ball screw nut 81 is rotatably supported on the cover housing 67 by bearings 84 and 85 near the switching gear 71. A gear 87 that meshes with the large diameter teeth 71A of the switching gear 71 is fixed to the lower end of the holder shaft 82 with a key 88, and rotation of the torque motor 60 is controlled by a ball screw nut.
81 can be transmitted. It goes without saying that the ball screw nut 81 is screw-fitted to the ball screw shaft 61. The transmission torque from the motor shaft 66 to the ball screw nut 81 is the switching gear 71.
There are two types depending on the upper and lower positions.

In FIG. 4, 90 is a pulse generator for detecting the rotating direction and the rotating speed of the ball screw nut 81, and is a disc fixed on the bottom surface side of the holder shaft 82.
91, light-emitting elements 92 and 93 and light-receiving elements 94 and 95, which are respectively arranged on the front and back sides of the disk 91. Disc 91
As shown in FIG. 8, transmission holes 96 and 97 are provided on the different radii which are separated from each other by an acute angle with respect to the center of rotation. On the rotation locus of the transmission holes 96, 97, a detection section composed of the light emitting element 92 and the light receiving element 94 and another detection section composed of the light emitting element 93 and the light receiving element 95 are arranged on the same radius. Pulse signals PULS1 and PULS2 are generated each time 97 passes between the light emitting elements 92 and 93 and the light receiving elements 94 and 95. The rotation speed of the disk 91 can be detected from its pulse period,
The rotation direction can be detected from the phase difference between the pulse signals PULS1 and PULS2. That is, when the disk 91 rotates right, the phase of the pulse signal PULS2 relatively advances, and when it rotates left, the phase of the pulse signal PULS1 relatively advances, and the rotation direction of the disk 91 is detected from the phase difference. It is supposed to be done.

FIG. 9 is a block diagram of the cargo handling balancer centering on the operation unit 15 and the control unit 13.

The operation unit 15 includes a start / stop switch 100 and a torque setting operation lever 10 for moving the link plate 9 up and down.
1, a numeric keypad 102, and a monitor display 103.

The control unit 13 is mainly composed of the CPU 104, and a ROM (read only memory) 1 in which operation programs and constant data are stored.
05, RAM (random access memory) used as a work area of the CPU 104 or a temporary storage area for data 1
06, input port 107, external bus interface circuit 108,
An A / D converter 109, a D / A converter 110, a timer / counter 111, a power amplifier circuit 114 that controls an energizing switch of a solenoid 76 that constitutes the electromagnetic brake, and a display controller 112 are commonly connected to a bus 113. There is.

The D / A converter 110 converts the drive control data for the torque motor 60 into an analog signal, and the motor driver 120 receiving the analog signal performs phase control to output a drive voltage to the torque motor 60. The drive voltage of the torque motor 60 is configured to be detected by the voltage detection circuit 121, the detected voltage is digitally converted by the A / D converter 109, and the conversion data is fetched by the CPU 104 at a predetermined sampling timing. It is supposed to be.

The timer / counter 111 inputs the pulse signals PULS1 and PULS2 output from the pulse generator 90 which is interlocked with the rotation of the torque motor 60, and detects the rotation direction and the rotation speed of the torque motor 60, that is, the ball screw nut 81. The number of rotations of the ball screw nut 81 during forward rotation or reverse rotation is counted up and down. For example, when the torque motor 60 rotates to the right, the ball screw shaft 61 descends, and when it rotates to the left, it rises.Therefore, the rotation direction of the ball screw nut 81 detects the up-and-down direction of the ball screw shaft 61. The vertical speed of the ball screw shaft 61 can be detected by the rotational speed. Furthermore, the vertical displacement amount of the ball screw shaft 61 can be calculated based on the count value of the normal and reverse rotation numbers of the ball screw nut 81. The up / down counter included in the timer counter 111 is initialized and reset when the activation is instructed by the activation stop switch 100, and the height of the lead screw shaft 61 at this time is the origin position. Therefore, the up / down counter uses the arm 9 whose origin is that position.
Up-counting and down-counting are selectively performed according to the vertical movement of the.

The control unit 13 performs vertical movement of the arm 9 according to the operation of the operation lever 101 and speed control thereof, and restraining control for holding the height of the arm at a desired position in accordance with a vertical movement stop command from the operation lever 101 and movement of the arm 9. Performs descent limit control at the lower limit of the movable range. The processing routine for the above control is started by the start / stop switch 100 instructing the start.

The operation lever 101 is configured as, for example, a potentiometer, and instructs the arm to stop at the neutral position of the lever, to move upward when the lever is upward, and to move downward when the lever is downward. The CPU 104 reads a command from the operation lever 101 in synchronization with a predetermined sampling timing assigned in the machine cycle, and gives data corresponding to the command to the D / A converter 110.
The motor driver 120 controls the phase of the drive voltage according to the data and drives the torque motor 60. Operation lever
When 101 is downward, the torque of the torque motor 60 decreases and the arm 9 descends rapidly without falling.
If the operating lever 101 is facing up, the torque motor 60
The motor is rotated counterclockwise due to the increase in the torque of the arm 9
Rises without rising sharply.

At this time, since the load torque corresponding to the load of the arm and the weight of the load acts on the torque motor 60, the rotation torque of the torque motor 60 is determined according to the load torque to control the ascending / descending speed of the arm 9. To do. The timer counter 111
For example, the period of the pulse signal PULS1 is measured, and the CPU 104 fetches the period and compares it with an expected value, and feedback-controls the motor driver 120 so that the ascending / descending speed of the arm 9 is constant.

When the operation lever 101 is returned to the neutral position, the CPU 104 is instructed to stop the arm 9. CPU1 given a stop command
04 controls the motor driver 120 so that the motor torque and the load torque are balanced and the rotation of the ball screw nut 81 is substantially stopped. In this control, based on the cycle data of the pulse signal PULS1 measured by the timer counter 111, the motor driver is set so that this becomes substantially 0.
The phase of the drive voltage is controlled to 120. When the stop command is issued and the stop state of the arm 9 is actually controlled to be constant (for a long time), the drive voltage of the torque motor 60 at that time is detected by the voltage detection circuit 121, and the A / D conversion data is detected. It is saved in the RAM 106, and then the solenoid 76 via the power amplification circuit 114.
Demagnetize and mechanically lock the ball screw nut 81 with an electromagnetic brake to prevent the torque motor 60 from overheating and power consumption. When the up / down movement of the arm 9 is commanded again, CP
The U104 promptly returns the drive state of the torque motor 60 to the state before the stop by utilizing the A / D conversion data of the drive voltage saved in the RAM 106, excites the solenoid 76, and drives the arm 9 as a motor. .

When the control unit 13 is started by the start / stop switch 100 and the timer counter 111 is initially reset, the count value of the up / down counter included therein is displayed on the monitor display 103 via the display controller 112.
Are sequentially displayed. The timer / counter 111 inputs the pulse signals PULS1 and PULS2 output from the pulse generator 90 in synchronization with the rotation of the torque motor 60, and rotates the ball screw nut 81 according to the forward / reverse rotation of the ball screw nut 81. Since the number is counted up and the counter is decremented, the displayed contents are gradually changed as the arm 9 moves up and down.

In order to perform the movement restriction control at the lower limit of the movable range of the arm 9, the position data for specifying the lower limit position of the arm 9 is input with the ten key 102. For example, actually carry the luggage supported by the arm 9 and check the height of the luggage delivery point on the monitor display 103.
Enter from 02. The data input from the numeric keypad 102 is held in the comparison value register of the timer counter 111, for example. After that, when the arm 9 is moved up and down within the same load carrying range, the timer counter 111 sequentially compares the comparison value with the count value of the up / down counter, and if they match, the same as the stop command from the operation lever 101. CPU stop command
Give to 104 by interruption. In this way, if the stop position of the arm 9 is set by operating the ten keys 102, the operator
Just operate the operating lever 101 with a rough guideline,
It is possible to stop the arm 9 at a constant height at all times. Therefore, if the luggage supply position and the carry-out position are unchanged, the trouble of manually operating the arm stop position in palletizing work or depalletizing work is released. As a result, work efficiency can be improved.

The upper limit stop position control of the arm 9 may use the limit switch 115 as shown in FIG.
You may employ the control by the input numerical value by the operation of 02.
In this case, an upper limit control comparison value register different from the lower limit control comparison value resist is prepared.

It should be noted that the external bus interface circuit 108 is not particularly required when the cargo handling balancer is used as a stand-alone, but for example, initial setting data for the control unit 13 and a status signal indicating an abnormality of the cargo handling balancer, etc. It is used when exchanging with the central control system of the production line or assembly line.

In the cargo handling balancer configured as described above, the output torque of the torque motor 60 itself has a certain limit due to its structure, and the maximum hanging load of the load is also limited accordingly. The maximum hanging load of the luggage at this time is
A torque that is given as required specifications of the balancer together with the maximum working range determined by the horizontal length of the arm 9 and is sufficient to raise and balance the arm 9 to which the load is applied at a predetermined speed from the motor shaft 69. The output torque of the torque motor 60 and the gear ratio of the drive unit 11 are determined so that they can be transmitted to the ball screw nut 81. At this time, when it is necessary to satisfy the required specifications for expanding the maximum working range under the same maximum suspension load, or when it is unavoidable to expand the maximum working range midway due to the nature of the target cargo handling work. , Simply increasing the horizontal length of the arm 9 causes the ball screw shaft 61
As a result of the increased distance to, the maximum suspension load is reduced. In order to avoid this in the present embodiment, the position of the switching gear 71 is slid downward from the position shown in FIG. 4, the small diameter teeth 68B of the driving gear 68 are meshed with the large diameter teeth 71A of the switching gear 71, and the motor The torque transmitted from the shaft 66 to the ball screw nut 81 is relatively increased. As a result, the adjustment of the joint portions 23C, 24C, 40C, 20C, 36D, 36E of the arm 9 and the drive unit 1
By the simple operation of changing the fixed position of the knob 89 in 1, it is possible to immediately respond to the request for changing the length of the arm 9 without causing a decrease in the maximum hanging load of the load and instability of the lifting speed of the arm 9. it can.

For example, the number of teeth of the driving gear 68, the switching gear 71, and the gear 87 is Z1 (the number of teeth of the large diameter tooth 68A) = 20, Z2 (the number of teeth of the small diameter tooth 68B) = 14, Z3 (the number of teeth of the small diameter tooth 71B). Number) = 18, 4Z (large diameter tooth 7
Assuming that the number of teeth of 1A) = 24, Z5 (the number of teeth of gear 87) = 21, and the number of rotations of the motor shaft 66 is N (rpm), the large diameter teeth 68A and the small diameter teeth 71B mesh as shown in FIG. In the first meshed state, the rotation speed of the ball screw nut 81 is about 1.23 N (rpm),
Then, in the second meshed state in which the small-diameter teeth 68B and the large-diameter teeth 71A are meshed, the rotation speed of the ball screw nut 81 is about 0.67N.
(Rpm). According to this, about 1.9 times more torque is obtained in the second meshed state than in the first meshed state.
Therefore, if the lateral length (distance from point E to point C in FIG. 1) of the arm 9 that satisfies the maximum suspension load W with the rated output of the torque motor 60 in the first meshed state is L, the arm is When the lateral length of 9 is extended to about 1.9 times L to expand the working range, by selecting the second meshing state, the maximum hanging load W similar to that in the first meshing state can be obtained. The rated output of the torque motor 60 can be satisfied, and the ascending speed of the luggage at that time is also stable.

The present invention has been described above in detail based on the embodiments, but the present invention is not limited to the embodiments, and various modifications can be made without departing from the scope of the invention.

For example, the structure may be changed such that only the first parallel link mechanism 21 is adopted as the arm. Further, the transmission of torque from the motor shaft to the screw nut may use not only a gear but also a toothed belt. In this case, the torque can be switched by changing the gear that stretches the belt.

[Effect of device]

The cargo handling balancer of the present invention has a variable arm length, and the transmission torque from the torque motor to the screw nut can be switched according to the set length of the arm. The torque switching mechanism of the arm drive unit increases the transmission torque from the torque motor to the screw nut to lengthen the arm to widen the work range to meet the various required specifications of the maximum work range. It is possible to change the setting of the torque transmission path, and easily meet various required specifications of such maximum working range without lowering the maximum hanging load of the load and destabilizing the rising speed of the arm. Moreover, there is an effect that it can respond quickly. Therefore,
Compared to the conventional technology that had to deal with individual design changes to meet various required specifications in the maximum work range, setting arm length and transmission torque during the manufacturing process such as before product shipment Since it is extremely easy to deal with such a situation, it is extremely effective in reducing the cost. Further, since the user can freely adjust and set the setting, the excellent effect that the change of work or process can be easily dealt with is exhibited.

[Brief description of drawings]

The drawings show an embodiment of a cargo handling balancer according to the present invention. Fig. 1 is a partially cutaway front view, Fig. 2 is an explanatory view of the state of an arm at a movable range limit position, and Fig. 3 is FIG. 4 is a vertical cross-sectional front view showing the joint structure of the arm and the arm drive unit, FIG. 4 is a vertical cross-sectional front view of the arm drive unit, FIG. 5 is a bottom view showing the sliding fixing structure of the switching gear, and FIG. FIG. 7 is a cross-sectional view seen from the direction, FIG. 7 is a perspective view showing an example of a joint portion of a lateral link, and FIG. 8 is a schematic perspective view of a pulse generator.
FIG. 9 is a block diagram showing an example of an operation unit and a control unit of the cargo handling balancer of the present invention. 9 ... Arm, 11 ... Drive part, 21 ... First parallel link mechanism, 23, 24, 4013 ... Horizontal link, 23C, 24C, 40C ... Joint part, 60 ... Torque motor, 61 ... Ball Screw shaft,
81 …… Ball screw nut, 71 …… Switching gear.

Claims (1)

[Scope of utility model registration request] A base end of an arm capable of holding a load at a free end is supported by a frame so as to be capable of moving up and down and rotatable, and is fitted to a screw nut that is driven in a forward and reverse direction by a torque motor. In a cargo handling balancer including an arm drive section that drives the arm up and down by the screw shaft, the arm has a joint section whose lateral length is variably set in the middle section, and the arm drive section is , A cargo handling balancer configured to switch the transmission torque from the torque motor to the screw nut according to the set length of the arm.